Why use additional one frame when training?

[applezy8866]

Dear, I found that in dataset.py: " if not self.test_mode: self.num_frames_per_sample += 1" and in tracker.py: "num_frame = img.size(1) - 1" so what‘s the usage of the additional frame?

[a1600012888]

It is not used for training more frames. Since I am adding velocity supervisions, the velocity groud truth is from the box position at next frame. That's why I need to load one more frame.